1. Technical Field of the Invention
This invention relates to a battery monitoring device that monitors a battery pack including a plurality of battery cells connected in series.
2. Related Art
There is known a conventional battery monitoring device which equalizes cell voltages of a plurality of battery cells forming a battery pack through discharge or charge-transfer in each battery cell so as to reduce a variation in cell voltage among the battery cells in the battery pack. Japanese Patent Application Publication No. 2006-166615 discloses a battery monitoring device intended to reduce electrical power consumption due to accidental discharge or the like which may occur during equalizing cell voltages of battery cells forming a battery pack. This battery monitoring device is provided with monitoring means (in particular, equalizing means) for monitoring cell voltages of the battery cells. The monitoring means includes a timer to stop an equalizing operation a predetermined time after start of the equalizing operation.
In the above conventional technique, however, when a failure occurs in the timer of the monitoring means, it becomes unable to stop the equalizing operation at proper timing, which may lead to accidental discharge or charge-transfer in each battery cell. Accordingly, in the conventional battery monitoring device, it is not possible to sufficiently ensure reliability during the equalizing operation.
In consideration of the foregoing, exemplary embodiments of the present invention are directed to providing a battery monitoring device that can equalize cell voltages of a plurality of battery cells forming a battery pack and can enhance reliability during the equalizing operation.